CUSTOMERS OF NatWest, RBS and Ulster Bank have been locked out of their online and mobile accounts.
Technical issues have downed the banks' online and mobile banking services, and some customers have also complained that their NatWest cards are not working at ATMs.
NatWest has been apologising to customers via its @NatWestHelp Twitter account.
"We're aware of some issues on our Online and Mobile Banking services and are working hard to fix them. Telephone Banking and ATMs are available. Sorry and thanks for your patience," says a tweet from 06:57 this morning.
RBS also confirmed the borkage in a statement, saying: "We are aware that customers are currently experiencing issues logging into their online and mobile banking accounts.
"We are aware of the problem and are working to fix the issue. Customers can still use ATMs and telephone banking."
Hannah Maundrell, editor in chief of money.co.uk commented: "Frustrating times for NatWest customers this morning, especially ahead of the weekend.
Banks really need to pull their socks up because this keeps happening again and again. It's really not good enough when so many customers are being encouraged to bank online. It's worrying when your bank can't keep on top of their IT systems."
The NatWest outage comes a day after Barclays customers were affected by similar service disruption which saw customers unable to access online banking, telephone banking and some branch services for up to six hours on Thursday.
Barclays is reported to be facing an investigation by the House of Commons Treasury Select Committee as a result of this systems failure.
Commenting on the Barclays outage, Lev Lesokhin, SVP strategy & analytics at software vendor Cast, said UK banks seem to be unusually vulnerable to such glitches, which are often due to software failures.
"Banks in other geographies don't have as many problems as UK banks. Based on our research, UK banks don't do as good a job controlling the structural quality of their legacy systems. So the UK banking sector has some catching up to do in getting that kind of software intelligence," he said.
We will update this story as more details emerge.
Firm argues that Cupertino prevents devs from operating on equal terms
Under pressure, pushing down on me, pushing down on my screen
Keep an eye on that neighbour who's been talking about making a killer drone...
WiFi, why Delilah